Perfectly seasoned and cooked just right, the broiled grouper on the Texas menu last summer tempted Donna Schroeder to eat every bite.

The only problem? It was poisoned, tainted with a hard-to-detect toxin that produces symptoms so bizarre, they put peanut-linked
salmonella infections
to shame.

“It’s horrible, I’m telling you,” said Schroeder, 65, a retired Beaumont, Texas, realtor, who is only now recovering from the worst symptoms of ciguatera fish poisoning, an exotic foodborne illness that health officials say may be dramatically under-recognized in the United States.

The malady afflicts at least 50,000 people a year worldwide — and the real number may be 100 times that many. While ciguatera fish poisoning is largely unknown in most of the U.S., several recent cases have attracted growing concern, officials say. They hope a greater awareness will help alert consumers and doctors and improve treatment of the incurable illness caused by coral algae toxins that accumulate in large tropical reef fish.

Within hours of the July dinner, Schroeder was stricken not only with typical nasty food poisoning symptoms — diarrhea, vomiting and fatigue — but also with a dangerously slow heart rate and neurological problems that caused her hands and feet to tingle painfully and, oddest of all, reversed her sense of hot and cold. Some patients also say they feel like their teeth are falling out — and the symptoms can linger for years.

“Whatever I touched, if it was hot, it would feel cold. If it was cold, it felt hot,” Schroeder recalled. “I couldn’t walk on the tile floor. It felt like it was burning me.”

Brandon Gothier Photography

Donna Schroeder, 65, of Beaumont, Texas, had to diagnose ciguatera fish poisoning herself after doctors failed to recognize the illness.

That should have been a clue to emergency room crews and doctors, but it wasn’t, said Schroeder, who was sent home with a general diagnosis of food poisoning, but nothing to explain the odd reactions or why they lingered so long.

”Doctors don’t even know what it is,” she said. “How sad is that?”

Ciguatera fish poisoning often is missed, even though it is the most common seafood-toxin illness reported in the world, said Richard Weisman, a toxicologist and director of the Florida Poison Information Center.

“If you go to the Caribbean Islands, you can’t find anybody who hasn’t had it,” he said.

Residents there and in other tropical places — Hawaii, Guam, the Virgin Islands, Puerto Rico — know that large, predatory fish caught by sport fishermen on coral reefs are common sources of ciguatera fish poisoning.

The actual toxin is produced by microscopic sea plants, which are eaten by smaller fish that are, in turn, eaten by larger fish such as barracuda, grouper, sea bass and snapper. The toxins become increasingly concentrated as they move up the food chain.

Recent outbreaksIn the continental U.S., reported cases have been rare, typically confined to tourists who become ill after returning home from tropical vacations or to fishermen sickened by their own deep-sea catches.

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Recently, however, worries about the illness increased after it cropped up in unexpected places. In 2007, 10 people in St. Louis who ate imported fish at two restaurants were sickened with ciguatera.

Last year, several unspecified outbreaks of ciguatera linked to grouper and amberjack compelled the federal Food and Drug Administration to expand guidelines warning about the risk of ciguatera in fish caught in the northern Gulf of Mexico.

And just last month, food safety inspectors in Canada issued a health hazard alert for ciguatera-tainted frozen Leatherjacket fish after two people became ill in that country.

Symptoms mistaken for multiple sclerosis
Part of the problem is that ciguatera fish poisoning is hard to detect for seafood suppliers and consumers alike, said Melissa Friedman, a neuropsychologist at Mount Sinai Medical Center in Miami who studied victims of the illness.

“You can’t tell from the way it looks. You can’t tell from the way it tastes. There’s nothing you can do in terms of storage. There’s nothing you can do in terms of cooking,” she said.

Instead, people simply eat the toxic fish and become ill. Baffled doctors often confuse ciguatera symptoms with those of multiple sclerosis, or else they come away empty-handed, Weisman said.

“There are people having CT scans, MRIs, all these tests.” he said. “They do million-dollar workups, but no test will ever come back positive.”

Three-day window for best treatmentThat can delay one of the only treatments for the illness: an intravenous dose of a drug called mannitol, which can reduce or prevent the neurological symptoms. The drug is most effective, however, within the first 72 hours of illness, Weisman said.

The worst of the illness usually lasts for a week or two, and it's rarely fatal. But in some victims, the effects linger much longer, or never really go away. Many patients find that certain foods such as other fish, nuts or alcohol trigger relapses, and that overexertion can send the symptoms flooding back.

One of the most pressing problems with ciguatera is that, although the illness has been chronicled since Christopher Columbus' crew ventured to the New World, there is no baseline data about incidence — or prevalence.

Between 1998 and 2002, the federal Centers for Disease Control and Prevention logged only 16 foodborne outbreaks of ciguatera affecting 73 people in the U.S., a 2006 summary showed.

But only 2 percent to 10 percent of ciguatera fish poisoning cases are reported to authorities and many health officials don’t realize it’s a reportable condition, said Dr. Lora Fleming, a ciguatera expert from the University of Miami. Using data from Dade County, Fla., where about 50 to 60 cases are reported a year, experts estimate that for every single case of ciguatera detected, between 10 and 100 cases go unreported.

Just last month, the CDC launched the Harmful Algal Bloom-related Illness Surveillance System, a monitoring system that will track ciguatera in people and animals, among other things. First results aren’t expected for a year, however, said Lorraine Backer, a scientist with the National Center for Environmental Health.

One outcome of the project may be to further discussions of whether global climate change is influencing ciguatera outbreaks, Backer said. Some scientists believe that ciguatera is moving north as ocean waters warm, and that increased numbers of hurricanes and tropical storms may cause disturbances in coral reefs that make them more hospitable to the toxic algae.

'More prevalent than we think'In the meantime, it’s hard to convince victims like Donna Schroeder that ciguatera is not a serious, growing and misunderstood problem. She only discovered she had ciguatera poisoning by asking her daughter to research fish-borne food illnesses on the Internet and then matching her bizarre symptoms to those listed online.

“I feel it’s more prevalent than we think,” Schroeder said. “There’s a lot more of it and people are getting sicker.”

Schroeder has filed a lawsuit against the place where she ate the meal, the Stingaree Restaurant in Crystal Beach, Texas, and against Katie’s Seafood Market of Galveston, Texas, which supplied the seafood.

The legal action was inspired mostly by a desire to raise awareness about the illness, Schroeder said. “I really wanted to get the word out about this fish,” she said.

But other victims have been less altruistic. Todd Stewart, a lawyer in Jupiter, Fla., has handled a dozen ciguatera cases in the decade, including the largest-ever settlement for the illness in the state’s history. It was in the six figures, he said, declining to be more specific.

Stewart argues that seafood suppliers and restaurants have an obligation to research so-called “ciguatera hot spots,” places in the world where the ciguatoxin is common, and to avoid buying fish from there.

“They ought to be asking: Did you take this from a ciguatera area?” he said. “You could potentially be exposing customers to a poisonous fish.”

Brad Vratis, general manager of the Stingaree Restaurant, said he couldn’t even pronounce “ciguatera” before he learned of Schroeder’s illness. “We haven’t served a piece of grouper in this restaurant since then,” Vratis said.

It can be tough for consumers to protect themselves against a poison that can’t be detected and can’t be killed by freezing or cooking. At least one Hawaiian company, Oceanit Laboratories Inc., markets a $30 ciguatera fish test kit that claims to successfully identify the toxin within an hour, said Dr. Joanne Ebesu, a senior scientist with the company.

But the paper co-authored by Friedman and Fleming concludes that no commercially-available fish testing product has been proven to be accurate by independent tests.

Mostly, Fleming said, consumers are on their own.

Fish-lovers hoping to avoid ciguatera poisoning can take a couple of steps. First, ask where the fish is from. If a restaurant or supplier can’t say, be wary.

Second, eat small portions of different fish instead of larger servings of a single fish. That will perhaps lessen the dose of any toxin present.

Finally, consider avoiding certain fish altogether.

“Personally, I don’t eat large reef fish,” said Fleming. “And I don’t eat fillets of fish because I don’t know what the original fish was.”